Use Qiskit Ecosystem theme

[frankharkins]

Summary

Updates to the new documentation theme. This is a draft PR to test docs build times.

• Total file size increased by ~505% (5mb -> 27mb)
• Build time increase by ~1512% (58s -> 877s)

[coveralls]

Pull Request Test Coverage Report for Build 5941753047

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 87.856%

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Totals
Change from base Build 5926831729:	0.0%
Covered Lines:	9810
Relevant Lines:	11166

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💛 - Coveralls

[mrossinek]

• Build time increase by ~1512% (58s -> 877s)

Just curious: are there any plans of addressing this? That build time is a bit excessive.

[Eric-Arellano]

Just curious: are there any plans of addressing this? That build time is a bit excessive.

Yeah, this is still a draft because we first wanted to see how bad the hit was. For some repos, it's faster to use the new theme! For others like Qiskit or this repo, it's much slower naively.

We have a few techniques to work around this. Only haven't had time yet to implement it. We have an intern starting soon who we're hoping can help switch projects over :)

[mrossinek]

@frankharkins Given qiskit-community/qiskit-nature-pyscf#44, can we expect this PR to move forward, too?
What do the timings look like with the latest version of the theme?

[Eric-Arellano]

@mrossinek, yes, @arnaucasau is a new intern at IBM and his first main project is to switch all the Ecosystem projects to the new theme 🙌 He's triaging if switching results in slow downs. When it does slow down, there are things we can do like reorganizing API docs to speed it up. He'll be helping projects out with that.